I believe the Radeon R5 230 (Caicos Pro) is in the same family as the Radeon HD 5xxx series. It's not GCN (Graphics Core Next) if that matters to you. I think the main draw of GCN cards is that they will continue to be supported going forward and anything pre-GCN is end-of-life.
I really like the Radeon HD 77xx series and the R7 series but they tend to be kind of expensive, especially for low-profile models, if you can even find someone selling one (used).
I don't really know much about running GroovyMAME on a TV via component. You should probably revise the title of your original post to provide that information so people can see what you're trying to do before clicking on your thread.
Make sure you update your original post with details about your hardware, monitor (include the model number), operating system choice, etc... The more specific details you provide about what you have and what you're trying to do, the better the responses will be.